1. Field of Invention
This invention relates to apparatus for transporting strip material such as paper or plastic film trim from a first location to a second location.
2. Description of the Prior Art
During paper and plastic film manufacture trim is often cut from an edge or edges of the web material during manufacture or conversion.
There are essentially two basic conventional trim handling systems, namely the continuous ribbon system and the chopped trim system. In the continuous ribbon system air from a fan or blower enters a venturi-type ejector where, due to flow acceleration, sub-ambient pressure is generated. A vertical duct or downspout connects this low pressure region with a trim receptacle mounted near the trim slitter mechanism. The venturi and the fan are sized to provide sufficient pressure differential so that the velocity of the entrained downspout flow exceeds the trim speed by at least 500 fpm and preferably by at least 1000 fpm. In order to provide sufficient entrainment the fan static pressure must be approximately 41/2 times greater than the duct pressure loss. Since the duct pressure loss increases with both the air velocity and the duct length, high speed conveying of continuous trim ribbon over long distances becomes difficult if not impractical. The main problems are: expensive blowers, high energy consumption, and excessive noise produced by the venturi ejector.
Problems also exist relative to the chopped trim system wherein the downspout is connected directly to the fan inlet. As the trim ribbon passes through a specially designed fan blade it is cut into small pieces which are then conveyed into the fan exhaust. Although such a trim handling system operates at low horsepower and is somewhat less noisy than the continuous ribbon system, the trim handling at the exit requires either a large efficient cyclone or a baler, arrangements that are both labor and capital intensive and require large working spaces.